With the utility and flexibility provided by the current level of technological development in the art of wireless communications, there will often be circumstances where a large number of communicators, using such wireless technology, must be interfaced and managed. In a typical situation, those communicators would be arranged into a plurality of networks, of nets, according to some commonality of interest among members of a given net, and often such nets will be arranged in accordance with a predetermined hierarchy. A frequency plan will be developed for allocating transmission frequencies among the various nets in a manner intended to avoid interference among simultaneous transmissions. It will also frequently be the case that transmissions among such communicators are desirably encoded to avoid interception of the communicated intelligence by electronic "eavesdroppers". Thus a security plan may also be required governing the establishment and assignment of the codes used for such encoding. Because such codes may occasionally be broken or otherwise compromised, a facility must also exist in the communications management structure for periodically changing the codes in use by all, or some substantial portion of the communicators.
A typical environment requiring application of such communications management/planning methods would be a military exercise, where a large number of personnel and equipment would be deployed in a relatively small geographical area, and having a multiplicity of diverse communications requirements. Except as the context requires otherwise, such a military communications environment will be assumed hereafter as the underlying communications environment for the discussion to follow, both as to the current state of the communications management art and the novel communications management system of the invention. It will be apparent, however, to those skilled in the art that the system of the invention will also find ready application in the public safety environment, as well as in many industrial operations.
As background for illustrating the general communications management process in a complex communications environment such as described above, we will first describe the essential elements involved in the planning/management of such a communications system. In such an exemplar communications environment, the planning process would typically involve four major categories of such planning: (1) network planning, (2) frequency planning, (3) security planning, and (4) distribution planning. We will consider each of those planning categories in turn below.
I. Network Planning
The network planning function includes the collection of communications data generally related to the expected operating environment as well as data specific to an operations plan for the operation to be supported by such a communications system. Included in such data will be information on: (1) user requirements, (2) RF emitters alien to the communications system which are expected to be found in the planned operating environment, (3) communications gateways to related operations, and (3) unit location changes from a pre-planned system. Because the operations plan will generally be subject to change as it is further refined to accommodate actual conditions found in the operating environment, the communications plan must also be capable of change in response to new information in respect to the operating plan. In the typical case, communication requirements and user needs will flow from lower levels in a communications hierarchy up to higher levels in that hierarchy, where network planning is being performed. Such planning data may include information on units to be deployed and available radio equipment, netting requirements, deployment locations, and local frequency use.
Once a more-or-less complete set of data respecting communication requirements for the planned operation has been obtained, the communications planner will then assign radio users and equipment to nets. As will be appreciated, in the absence of some form of automation, this assignment process will involve manual, often error-prone activities typically using pencil and paper. For a system typical of the complexity to which the communications management system of our invention would be applied, several thousand radios arranged into several hundred nets are likely to be involved. Thus, it can readily be seen that the task of tracking each authorized user, the radio equipment assigned to each net, and the numbers of nets assigned would be a time-consuming burdensome process.
As a further step in the network planning process, analysis of terrain for propagation studies and line-of-sight analysis may be required for some or all of the mobile radio units involved in the communications system. In some cases, a retransmission site may be needed for placement of a relay station to extend the range of communication.
Inherently, changes in the operating and communication plans will continue to occur to accommodate anomalies which were not considered in the original plan. The network planning function must include sufficient flexibility to accommodate such continuing changes.
II. Frequency Planning
To enable efficient and optimal usage of the available radio frequency spectrum, a frequency plan must be developed. The frequency planning function involves three essentially distinct subfunctions: allocation, allotment, and assignment of frequencies.
Frequency allocation describes the portion of the RF spectrum that a country or region is lawfully permitted to use and will usually have been established by national and/or international agreement. That frequency allocation defines the primary, second, and permitted usage in each frequency band.
The frequency allotment for a particular environment would be derived from the frequency allocation for the country or region where that operation is being conducted. Normally, such a frequency allotment would be established pursuant to domestic policy for that state or region.
The assignment of frequencies for individual users and/or nets will be determined by the network planner, and will be derived from the frequency allotment for the operations area.
It will be readily understood that, through proper frequency planning, a number of desired objectives may be achieved. Such objectives include: (1) reduced interference and conflicts within the local RF spectrum, (2) increased optimization of spectrum resources, (3) increased number of useable communications channels, and (4) organization and tracking of assignments. Moreover, since the operating environment for a communications system of the complexity under consideration here is highly dynamic, it is important that the communications planner be able to modify and regenerate a frequency plan quickly and easily.
Another frequency-related task to be addressed by the communications planner is the avoidance of restricted frequencies within the frequency allotment for the operations area. In many cases, there will be restrictions on individual frequencies such that those individual frequencies are not available for use by the planned communications system. Typical of such restricted frequencies will be those used for commercial, radio and television, safety and emergency services, special use frequencies, and, where operating in hostile territory, known RF jammers. Such restricted and reserved frequencies would be removed from the allotment by the frequency planner, thereby yielding the useable allotment as the starting point for assigning frequencies for the communications system of the planned operation.
The communications planner must then consider the various transmission/reception modes to be supported by the communication system. In virtually all cases, a single channel ("SC") transmission/reception mode will be supported and will require the assignment of frequencies for such single channel operation. However, it will frequently be the case, particularly in the military environment, where a spread-spectrum transmission/reception mode will also be extensively used, with such spread-spectrum communications typically being of the frequency-hopping type. For such frequency-hopping ("FH") spread spectrum communications, frequency hopsets--i.e., the band of frequencies used by a particular FH net--and lockouts--frequencies which are prohibited from use by an FH net--must also be established by the communications planner.
When planning frequencies for the single channel mode, particularly as related to the HF band of frequencies typical for such single channel operation, the communications planner will select channels from the frequency allotment which are within the range of the recommended Lowest Useable Frequency ("LUF") and Maximum Useable Frequency ("MUF") for the band, preferably close to the Frequency of Optimum Transmission ("FOT"). These values must be determined by using current sunspot numbers and solar flux values.
Additionally, when designing single channel communications nets, the communications planner must consider cosite interference, such as harmonic and intermodulation interference. By using proper frequency and distance separation, the planner will be able to design a reliable communications net which largely avoids such interference.
In the case of the frequency-hopping transmission/reception mode, the frequency planning process begins by identifying the available allotment. It will usually be the case that frequency hopping transmitters will not interfere with single channel receivers as long as they are not collocated. However, there may be some single channel frequencies that are desirably removed from the frequencies in use by such a frequency hopping transmitter. After removal of such frequencies from the frequency allotment, the communications planner will precede to generate the hopsets and lockouts for the frequency-hopping nets.
As indicated above, FH lockouts define frequencies that must not be used in the frequency-hopping mode, while FH hopsets define the frequencies that can be used in a particular frequency-hopping net. In order to reduce the possible effects of jamming--one of the advantages of the frequency-hopping mode, the communications planner will also attempt to select frequencies spread across the allotment for the frequency-hopping mode. It will be appreciated that a manual creation and modification of hopsets and lockouts for a frequency-hopping radio is impractical and that automation should therefor be employed for this function.
Finally, it will be understood that the ability to establish and maintain communication within a given frequency band can vary greatly depending on many environment conditions, such as time of day, sunspot activity, terrain, etc., as well as the level of cosite and harmonic interference. Noteworthy as well, is the fact that the use of frequency-hopping radios places a greater demand on the amount of spectrum resources needed. All of these elements contribute to an increased level of analysis required of the communications planner in an effort to optimize the communications system being managed.
III. Security Planning
After a workable frequency plan has been developed by the communications planner, considerations of security for the communications exchanged within the communication system will be a logical next step. It is noted that the planning sequence of performing frequency planning prior to security planning will generally be reasonable since the need for re-planning at the network level is more likely to occur due to frequency conflicts than to changing security requirements.
As previously indicated, a security regime will often be desired to prevent interception of the communicated intelligence by third parties, particularly hostile third parties. Typically, such security is provided by an encoding-decoding scheme whereby the transmitted information is encoded using a code known to the authorized receivers, and decoded by those receivers. In the case of the frequency-hopping mode, such encoding will ordinarily by applied to the sequence of frequencies utilized for a particular frequency-hopping transmission. For single-channel mode, the transmitted signal, which generally will have been converted to digital form, will be modified in accordance with the selected code and the receiver will be adapted to remove the coding information from a received signal, thereby recovering the communicated intelligence. In many cases, the encoding scheme will utilize a form of cryptography, where the coding is determined from a "key" supplied to the user. Because such keys would ordinarily be provided as a series of variables--as a means for providing increased security against deciphering of the key, they are commonly designated as crypto-variables. For convenience we will hereafter refer to the electronic coding of data used by the transmitters/receivers of a communications system in terms of such crypto variables (or, alternatively, crypto-keys). It will be understood, however, that other forms of encoding for providing communications security for the net could as well be used consistent with the intent and purposes of our invention.
There will generally be two types of crypto-variables used in a communications system of the scope and type discussed herein. The first type will be used to provide encryption and decryption of message traffic on a communications link within the communications system, and will be designated herein as a Crypto-Variable ("CV"). The other type will be used to provide encryption and decryption of CVs during the process of downloading such CVs from a network-level source to individual transmitter/receivers within the network, and where such downloading is itself accomplished via a radio link, thus being subject to interception. This type will be designated as a Remote Crypto-Variable ("RCV"). As will be known, crypto-variable are identified electronically by a unique "Tag".
The communications planner must continuously be aware of changing requirements and the effects of those changes on the security plan. For example, a need may be identified for two members (i.e., users) in different nets to communicate. Through replanning at the network level the situation could be handled in one of two ways. Either those two members could be connected into a new net, or one of the members could be included in the existing net of the other member. The first approach would require additional communications parameter information (hereafter "Communications Information" or "CI"), including additional crypto-variables and possibly additional frequencies. The second approach generally uses existing CI.
In the absence of automation, the communications planner would typically be required to make a cross reference list such as the following:
To each net (and each net member), the planner must assign a crypto-variable tag. Continuous checking must be performed to avoid assigning more crypto-variable tags to a member than its transmitter/receiver can accommodate. Also the planner must be aware that policy or operating constraints may limit the number of members in a net. For each net member, the planner typically must provide a different Remote Crypto-Variable, in order to facilitate remote recovery from the circumstance of one member having been compromised--e.g., its CV having been learned or its transmitter/receiver equipment having been obtained by an alien interest. The concept of "recovery" from such a compromise, as used herein, generally relates to the loading of new security codes into the transmitter/receivers for the non-compromised users in a net.
It can thus be readily seen that there are a large number of crypto-variables (CVs and RCVs) which must be managed and tracked. For example, in a communications system comprising three hundred nets with an average of ten members per net, the number of CVs will be three hundred and the number of RCVs can be as high as three thousand.
Each communications plan will have a mission associated with it. Generally, within that mission, each crypto-variable must be changed or updated on a regular basis according to a pre-determined policy. Such changes are called crypto-variable supersession. Thus, the communications planner must also be aware of the usage period for each crypto-variable and must plan accordingly for the successive versions. Typically, the CVs and RCVs have different usage periods.
IV. Distribution Planning
Once the Communications Information (principally frequency and security data) for all of the members and nets comprising the communications system has been determined, that CI must be loaded into the transmitter/receivers of each of the members, a process referred to as "fill"--for filling (or loading) the CI data into the member transmitter/receivers. In a complex communications system, the large number of equipment assignments and the need to transport data and devices complicate the distribution of CI from a planning site.
Planning the distribution of the data generally consists of two parts:
Fill connectivity analysis discovers what paths are available for this distribution. Fill routing assigns information along such paths.
To identify fill connectivity, the communications planner must analyze the resources available to hold and transfer fill data, including the data source, fill devices and destination radios. Then, an analysis is required to determine realistic distribution paths allowing for geographic separation, schedule differences, and organizational barriers. Travel or transmission time will also be considered in the analysis. Finally, the planner creates a connectivity "map" showing the potential paths between the data source and the destination radios.
Fill routing assigns the paths on such a connectivity map for each item of Communications Information to reach its intended destination radio. Several constraints will guide or limit the communications planner performing this routing. To begin with, fill devices have a finite capacity. And, for security reasons, they should not contain more information than needed to meet their delivery missions. The communications planner will create a distribution plan that routes the required Communications Information efficiently over the connectivity map allowing for the capacities and other constraints applicable to the devices involved. The planner will then break the plan into specific instructions for each field device operator.
V. Frequency and Security Data Distribution
After all of the network, frequency and crypto-variable planning has been performed, the resulting CI must be distributed to the proper communications equipment. As the net size increases, this task becomes very time consuming and error prone. The distribution must be organized so that all members of a given net receive the CI for that net in a timely fashion. As will be appreciated, this task is almost impossible to accomplish accurately without some form of automation.
The CI will initially be distributed throughout the networks of the communications system by using a set of fill devices. The distribution would ordinarily take the form of a hierarchical structure, where master fill devices are downloaded with CI from the planning system, and pass parts of such downloaded CI data to subsidiary fill devices at lower hierarchial levels. These subsidiary fill devices, in turn, may fill certain communications equipment and also pass part of their CI data to other fill devices, and so on down the defined hierarchy.
VI. Post-Distribution Planning/Management
Once the CI for an operational plan has been distributed, another phase of planning (or, more properly, replanning) is entered: the updating and management of the communications plan. During this phase, the communications planner must continuously respond to dynamic changes in the operating environment for the communications system.
As an example of such changes, the frequencies in use by the communications system may need to be modified to account for either non-hostile RF emitters, which arrived in the operations area subsequent to the initial frequency planning process, or the jamming of one or more of the initially selected frequencies by hostile interests. While certain remedial actions may be appropriate at the user level, such as increasing a transmitter's power level or switching to a different net, it will often be necessary for the frequency planner to take action, such as replanning the net frequencies, or coordinating frequency/time usage with the non-hostile emitters.
In some cases, because of environmental changes, such as weather, solar flux, etc., radio communication in the operations area will be degraded. In that circumstance replanning must be performed starting with an analysis of signal propagation under the various current conditions. Such analysis will result in a selection of a modified frequency allotment which is more optimized to the current environmental circumstance. New CI will then be generated for the affected communications nets to include such selected new frequencies.
Throughout an operational mission, changes can also occur in the net structure required to support various operations. Members, or groups of members, may be geographically relocated and/or attached to different operational units, and thus the netting requirements may change. Such changes will usually be addressed by providing the relocated members with the CI for the new nets with which they are now associated. In some cases, however, geographic considerations will require the use of different frequency allotments.
As noted previously, most, if not all, of the crypto-variables will be periodically superseded, requiring that the communications planner perform certain tasks prior to the expiration date of the crypto-variable. First, the expiration dates of all distributed crypto-variables must be tracked so that enough time is available to generate and distribute new supersession crypto-variables prior to the end of the usage period for existing crypto-variables. Then, the supersession crypto-variables must be generated, associated with appropriate key tags, and distributed to the end users. In the absence of automation, these task are so burdensome that there would be a tendency to stretch the usage period for crypto-variables, thereby potentially compromising security in the communications system.
A further major on-going task for the communications planner is the reestablishment of communications security in the event of a security breach of one or more units of the communications system. In general, a communications security breach can be defined as a loss or gap in planned protection against unauthorized communications. It will be understood that even a suspected loss must be corrected for continued confidence in the net security. Such a breach could arise through loss of hardware containing CI, or by loss of the CI itself.
If a security compromise occurs, the communications planner must identify the extent of the compromise and choose a strategy to restore protection to the compromised network, such as by invalidating the compromised equipment and/or changing the crypto-variables for all authorized users. The planner must then identify what CI needs to be changed, and generate appropriate replacement information. Delivering that new information may involve identifying new distribution paths, and then making the distribution. As with the initial distribution, the process may use fill devices which directly load the new CI into the transmitter/receivers to be modified, or it may be remotely loaded into transmitter/receivers not having ready access to such a fill device via a radio link protected by an RCV.
From the foregoing discussion of the planning and management process for a system addressed to the communications requirements of a complex operational scenario, it will be apparent that two desirable objects in respect to such communications system will be: (1) an automation of the various planning/management functions which must be carried on, and (2) an integration of such functions into a common structure or architecture. While a degree of automation for some of these functions has been achieved in the prior art, nothing comes close to an integrated automation of the full communications planning/management function.
For example, software has been developed (ITT Export Hopset/COMSEC Key Generator Software) to provide frequency hopset and security key generation for a specific spread spectrum radio set, but such software does not address network management, distribution/asset management or CI generation management. Neither does this prior art software take other cooperating nets into consideration nor is it able to address single channel communications equipment.
A U.S. Army system identified as "RBECS" operates to facilitate frequency and CI generation for U.S. Army SINCGARS radios but does not support net management, key generation and management, or distribution/asset management functions.
The U.S. Army "Net Planner" software allows for net planning, key tag generation and limited distribution/asset management functions, but does not support frequency generation and management, key generation, and CI generation and management functions.
A proprietary system of Crossbow Management Systems only operates with specialized hardware because it distributes planning and management functionally across multiple equipment platforms, and, as well, targets its management functions to specific equipment in the Crossbow family.
A software/hardware system designated as "ISYSCON" provides planning and management functions across multiple workstations networked together at a local planning sight and may be interfaced only with specific equipment in the U.S. Army ACUS, CNR, and ADDS systems.
While it might be possible to cobble together various of these prior-art approaches to achieve some form of automation for most of the planning/management functions described above, such an approach certainly would not represent an integrated approach to communications planning and management and would inevitably result in substantial duplication of functions among the various software and hardware systems so cobbled together. Moveover, such a combinatorial system would be limited to working with the least common denominator of the various different systems with which such prior-art approaches are designed to operate.
Accordingly, it is an object of this invention to provide a fully integrated and automated communications management system capable of addressing all of the communications management/planning functions described above, and being operable with essentially the full universe of communications equipment which might be expected to be used in such a communications system.